-LRB- CNN -RRB- -- Nearly 35 years after a Texas judge sentenced him to death , Ronald Chambers was found dead Monday morning on the floor of his cell .

Guards found Chambers , 55 , unresponsive around 6:30 a.m. while doing their rounds , Dallas County Sheriff Spokeswoman Kim Leach said . He was then transported to Parkland Memorial Hospital in Dallas , where he was pronounced dead .

The Dallas County medical examiner 's office said it would take six to 12 weeks before Chambers ' cause of death could be definitively determined . But Leach said Chambers had many health complications when he came last year to the Dallas County jail .

Chambers was 19 when he and Clarence Ray Williams kidnapped Mike McMahon and his date from the parking lot of a Dallas nightclub , then ordered them down the embankment of the Trinity River , according to the Texas Attorney General 's Office . The two men robbed the couple and , after shooting at them , left them for dead .

The female survivor , Deia Sutton , testified that she and her boyfriend survived the first attack , but Chambers went back and killed McMahan by repeatedly hitting him over the head with the barrel of a shotgun .

On December 18 , 1975 , a jury found Chambers guilty of capital murder and a judge subsequently put him on the state 's death row .

The Texas Court of Criminal Appeals twice set aside his conviction -- once because he was n't read his Miranda rights after being interviewed by a state psychiatrist -- but both times he was retried and convicted again .

In 2007 , the U.S. Supreme Court again granted Chambers a stay of execution , amid questions about the instructions given to the jury , the Dallas Observer reported . The case was sent back to Texas and a fourth sentencing trial was set for spring 2011 , according to published reports .

While numerous reports called Chambers the `` Dean of Death Row , '' because of the various legal maneuverings he did n't have a death sentence the entire time he was behind bars , including at the time of his death . Excell White , who killed four people in 1974 and was n't executed until 1999 , spent more time -- 8,854 days -- on death row before being put to death than any other Texas convict .

Texas , which has executed more prisoners since 1976 than any other state , pays $ 86.08 to execute a death row inmate , or the cost of drugs used in a lethal injection , the state 's Division of Criminal Justice reports . That compares to the $ 17,338 , on average , that it costs to jail a Texas inmate for 12 months , according to 2009 data from the National Institute of Corrections , which is below the national yearly average of $ 28,689 .

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Ronald Chambers was found on the floor of his cell and later pronounced dead

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He was convicted of capital murder in 1975 , then sentenced to Texas ' death row

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Chambers ' conviction was twice set aside , but he was later convicted again